This invention relates generally to the field of medicine, and more particularly to implantable devices for delivering therapeutic agents to a body.
Localized drug therapy has been shown to be successful for chronic pain treatment and chemotherapy for spinal disorders using less drugs and without the potential adverse effects of a systemic dosage. Pumps for abdominal implant have been designed to dispense drugs as either continual dosage through a constant pressure, non-electrical means or as programmable, periodic dispensing through the use of an electrically driven pump and constant pressure reservoir.
More recently, the value of localized drug therapy for neurological disorders has been identified. Existing pumps, while potentially providing the therapeutic advantages of implantable infusion pumps, are large and are implanted abdominally. Such pumps if used will require a catheter tunneled from the abdominal implant site, through the neck to an entry site in the head, and then to the localized treatment site.
Present electrically powered pumps use primary (non-rechargeable) batteries as their power source. When the battery is depleted in these devices, the complete assembly must be removed and replaced. Rechargeable batteries have been used in previous implant devices including earlier pacemakers and present day artificial hearts and left ventricular assist devices (LVAD""s). Artificial hearts and LVAD""s require the use of an external power source due to the high power demand of the pumping system that would deplete an internal battery quickly. They also use a rechargeable battery to provide power for a patient when external power is not appropriate, such as when taking a shower or bath. Earlier pacemakers used a nickel cadmium rechargeable battery system that relied on the patient to recharge transcutaneously on a periodic basis.
According to one aspect, the present invention provides method and apparatus for retaining a reservoir for a therapeutic agent between the scalp and cranium of a subject. According to another aspect, there is provided method and apparatus for dispensing the therapeutic agent from the reservoir to a location in the body of the subject. According to yet another aspect, there is provided method and apparatus for pumping the agent to the location in the subject""s body with a pump. According to still another aspect, there is provided method and apparatus for forming at least one cavity in the cranium of the subject, and placing at least a portion of the pump in the cavity. According to still other aspects of the method and apparatus, power is supplied to the pump. These and other aspects of the invention are described below.